Dehydrofluorination Process of Poly(vinylidene difluoride) PVdF-Based Gel Polymer Electrolytes and Its Effect on Lithium-Sulfur Batteries
Julen Castillo,
Adrián Robles-Fernandez,
Rosalía Cid,
José Antonio González-Marcos,
Michel Armand,
Daniel Carriazo,
Heng Zhang,
Alexander Santiago
Affiliations
Julen Castillo
Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Vitoria-Gasteiz, Spain
Adrián Robles-Fernandez
Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Vitoria-Gasteiz, Spain
Rosalía Cid
Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Vitoria-Gasteiz, Spain
José Antonio González-Marcos
Department of Chemical Engineering, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Campus de Leioa, Barrio Sarriena, 48940 Leioa, Spain
Michel Armand
Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Vitoria-Gasteiz, Spain
Daniel Carriazo
Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Vitoria-Gasteiz, Spain
Heng Zhang
Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Alexander Santiago
Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Vitoria-Gasteiz, Spain
Gel polymer electrolytes (GPEs) are emerging as suitable candidates for high-performing lithium-sulfur batteries (LSBs) due to their excellent performance and improved safety. Within them, poly(vinylidene difluoride) (PVdF) and its derivatives have been widely used as polymer hosts due to their ideal mechanical and electrochemical properties. However, their poor stability with lithium metal (Li0) anode has been identified as their main drawback. Here, the stability of two PVdF-based GPEs with Li0 and their application in LSBs is studied. PVdF-based GPEs undergo a dehydrofluorination process upon contact with the Li0. This process results in the formation of a LiF-rich solid electrolyte interphase that provides high stability during galvanostatic cycling. Nevertheless, despite their outstanding initial discharge, both GPEs show an unsuitable battery performance characterized by a capacity drop, ascribed to the loss of the lithium polysulfides and their interaction with the dehydrofluorinated polymer host. Through the introduction of an intriguing lithium salt (lithium nitrate) in the electrolyte, a significant improvement is achieved delivering higher capacity retention. Apart from providing a detailed study of the hitherto poorly characterized interaction process between PVdF-based GPEs and the Li0, this study demonstrates the need for an anode protection process to use this type of electrolytes in LSBs.
